In relatively small sewage disposal systems, on the order of 100,000 gallons per day or less, sewage effluent from a sand filter or settling tank is generally passed to some public water-way. Chlorine is added to the sewage effluent to destroy odor, color and bacteria to insure against pollution of the public water-way.
Normally, liquid chlorine or a hypochlorite solution is employed as a bactericidal agent for the sewage effluent. Available equipment is costly and requires constant attendance. In northern climates when hypochlorite solutions are employed, they frequently freeze and the effluent remains untreated.
The present invention relates to apparatus and methods to treat sewage effluent which is inexpensive and needs no constant attendance. The apparatus comprises a rack fabricated of a material impervious to both sewage effluent and a chlorine releasing bactericidal agent, preferably fabricated of plastic containing tablets of trichloroisocyanuric acid. The rack is seated within a conduit for the flow of sewage effluent. The tablets are positioned in a row generally along the direction of effluent flow. The tablets extends generally transversely across a substantial portion of the conduit so that the greater the depth of effluent in the conduit, the greater the surface area of tablets exposed thereto.
The number of tablets employed in a row is a function of the demand for bactericidal agent which must be satisfied. In periods of relatively high effluent flow rate, the tablets may be nearly or completely submerged thereby dissolving at a maximum rate. However, at low flow periods only a small portion of the tablet would be exposed and a correspondingly low rate of dissolution experienced.
The bactericidal agent is trichloroisocyanuric acid which, in the presence of water, forms the familiar hypochlorite solution leaving cyanuric acid which is tasteless, odorless, colorless and non-toxic. Nevertheless, the trichloroisocyanuric acid must be mixed with an additive to insure a constant rate of solution otherwise, the trichloroisocyanuric acid tablets tend to dissolve erratically.